An unreported cause of rupture of the extensor pollicis longus tendon.

Avulsion fractures of the index metacarpal at the insertion of extensor carpi radialis longus are rare. We report such a fracture and the resulting complication of division of the extensor pollicus longus tendon, by the avulsed bony fragment. Careful clinical assessment and appropriate radiological examination is needed to diagnose this rare fracture and internal fixation is recommended.